Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds meaningful context beyond annotations, namely that the explanation is 'deterministic' and limited to 'primary' NAICS, but it does not disclose output format, error conditions, or prerequisites. This is comparable to the 'date-range' case in calibration, so a 3 is appropriate.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, with the core purpose in the first and a boundary clarification in the second. No filler, every clause earns its place, and the structure is front-loaded and easy to parse.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool is simple (2 required string params, no output schema), and the description states the core purpose and a limitation. However, without an output schema, the description does not explain what the returned 'explanation' looks like or what happens if vendor_id is not registered, leaving some ambiguity for an agent deciding whether to call it.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, leaving the description to define vendor_id and opportunity_id. The description only implies that vendor_id refers to a 'registered vendor' and opportunity_id to an 'opportunity.' It does not explain ID formats, how to obtain valid IDs, or any constraints, so it only partially compensates for the absent schema documentation.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('Explain') and resource (deterministic primary NAICS overlap between a registered vendor and opportunity), and the closing clause 'Not an eligibility determination' further distinguishes it from broader judgment tools. This makes the tool's scope immediately identifiable.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives a clear when-not ('Not an eligibility determination') and implies when to use it (needs an explanation of primary NAICS overlap). It does not explicitly name alternative sibling tools, but the exclusion signals the boundary well enough for an agent to route correctly.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.